I am having the exact same problem as you, and is only happening (or at least more noticeable) when the camera is doing a travelling. I was only able to remove completetly this issue, doing the zoom by animating the FOV, instead of actually moving the camera.
It’s not actually a solution, but at least work.
Besides that, I have been testing it and found that reducing the RelativeDepthThickness value of the ScreenProbes (default value: 0.02) reduces the impact of this Lumen Flickering issue.
I have this Cvar in my MRQ:
r.Lumen.ScreenProbeGather.ScreenTraces.HZBTraversal.RelativeDepthThickness 0.005
Notice that it will also reduce the impact of your GI.
If you found any solution to this problem, please share it, because I am a little desperate too 